Process for preparing protocatechualdehyde

摘要

Protocatechualdehyde is prepared by the steps of reacting piperonyl dichloride with molecular chlorine in the presence of phosphorus trichloride, phosphorus pentachloride or sulfuryl chloride to prepare dichloropiperonylidene dichloride and hydrolyzing the dichloropiperonylidene dichloride. The piperonyl dichloride can be prepared by the reaction of piperonal with thionyl chloride in the presence of dimethylformamide.